Please find code here :-

For this you need to do add a domain in your Many2One like

product_id = fields.Many2one('product.product', string='Product', required=True,
domain=[('categ_id.name', '=', 'Software')])

In place of categ_id, write your category field name with .name to check by name(Ex: categ_id.name) and your value 'Hand Tools'

domain=[('your_categ_field_id.name', '=', 'Hand Tools')]

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